The core virology laboratory for the Yale adult ACTU will be located in the Retrovirus Diagnostic section of the national VA Virology Reference Laboratory at the West Haven VA Medical Center. This reference laboratory provides diagnostic virology services to over 100 VA facilities across the U.S. The laboratory is comprised of two sections, a general virology section and a retrovirus diagnostic section. The retrovirus diagnostic section provides diagnostic testing for both HIV-1 and HTLV-I, and routinely performs antibody, antigen and culture assays for HIV-1, as well as antibody assays for HTLV-I. Presently the retrovirus diagnostic section performs over 7,000 HIV-1 tests per year. Expertise and facilities are available in the general viral diagnostic section for isolation of CMV and other viruses, should these tests be indicated. The virology core laboratory will provide HIV-1 testing and store all samples from patients entered into the Yale adult ACTU trials. Specifically, the virology core laboratory will: (1) perform viral baseline tests prior to entry into the trial; (2) assess the effects of therapy on viral parameters such as viremia and plasma antigen levels; (3) expend all positive cultures for future susceptibility testing and antiviral resistance studies; (4) provide storage of all of patients' samples collected for viral studies and of all viral isolates obtained from these samples; and (5) test for other selected newly developed viral and surrogate markers as needed, and investigate their usefulness. The proposed virus core laboratory for the Yale adult ACTU trial unit is an established clinical laboratory that has also been involved in research and development, including antiviral research. Thus, procedures for specimen transport, labelling, storage and inventories, and methods for HIV-1 antigen and culture assays are already in place in the laboratory. Since it is a clinical laboratory, the laboratory is regularly inspected, is certified by the College of American Pathologists, and has a record of outstanding performance in both quality assurance and biosafety programs. The laboratory is proficient in handling large numbers of samples and is capable of conducting the number of tests required, provided additional personnel can be hired. Recently renovated space and equipment are available for the work proposed, with the potential for further expansion. Both key personnel engaged in the core virus laboratory program have expertise in the assessment and development of new diagnostic virologic markers.